Captive Screw With Integrated Biasing Insert
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Solution Overview
Problem
Existing captive screws often require a ferrule and exposed springs, which can be cumbersome and lack efficient mechanisms for securing the insert within the shaft, leading to potential separation issues and complexity in assembly.
Innovation Solution
A captive screw design featuring a shaft with a channel and hollow area, where an insert is movable and bookends the shaft, and a biasing member is positioned inside to maintain the insert's position, eliminating the need for a ferrule and ensuring secure fastening without external spring exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ferrule and exposed spring are used to secure the insert, then the insert can be retained within the shaft, but the assembly becomes more complex and cumbersome
Solution Approach 1:
The patent merges the ferrule and spring into a single integrated insert component. The insert includes a head portion that fits within the shaft and a tail portion that extends outward, eliminating the need for separate ferrule and spring components while maintaining the retention function through the biasing member's interaction with the insert's geometry
Solution Approach 2:
The patent extracts and eliminates the ferrule component entirely by redesigning the insert to perform both the retention and positioning functions that were previously distributed between the ferrule and spring assembly, simplifying the overall structure
2Reliability
If a ferrule is used to house the spring, then the spring is protected and positioned, but the overall fastener size increases and assembly becomes more difficult
Solution Approach 1:
The spring and ferrule are merged into a single insert component where the head portion houses the biasing member internally. The insert's head includes a cavity that contains the spring, eliminating the need for a separate ferrule while maintaining spring positioning and protection
Solution Approach 2:
The biasing member is nested within the head portion of the insert, which itself is positioned within the shaft. This nested arrangement allows the spring to be housed and protected without requiring an external ferrule, reducing assembly complexity
3Force
If the spring is exposed outside the shaft, then the insert can be biased, but the fastener appearance is compromised and protection is reduced
Solution Approach 1:
The biasing function and spring protection are combined by housing the biasing member within the insert's head portion. The head acts as both the structural element that provides biasing force and the protective enclosure for the spring, eliminating the need for external spring exposure
Solution Approach 2:
The insert's head portion serves as an intermediary structure that transmits the biasing force to the shaft while simultaneously protecting the spring. The head mediates between the spring's need to exert force and the need to protect the spring from external damage
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design provides a secure, simplified fastening mechanism where the biasing member maintains the insert's position within the shaft, preventing separation from the panel and eliminating the need for a ferrule, thus enhancing assembly efficiency and reducing complexity.
Implementation Method 1
a biasing member positioned inside to maintain the insert's position
Data Source
AI summary
One fastener has a shaft with proximal and distal ends. Threading extends along the shaft from the distal end, and a head is at the proximal end. A channel passes entirely through the shaft such that a first lateral portion of the shaft is on one side of the channel and a second lateral portion of the shaft is on an opposite side of the channel. The channel is inset from the distal end. A hollow area in the shaft extends from the distal end toward the proximal end. The hollow area has a width that is greater than a width of the channel, and a biasing member is positioned inside the hollow area. An insert has an interior portion and an exterior portion. The interior portion is configured for positioning in the channel and the hollow area, and the exterior portion is configured to be located outside the shaft.